Auto-replenishing, wound-dressing apparatus and method

ABSTRACT

Apparatus and methods to treat skin defects include a pump with reservoirs for a pressurization gas and a fluid, the fluid loaded at a factory and sealed or filled at point of use through a valve, septum, or the like. Upon activation, the pump generates a gas introduced into the gas reservoir, a movable wall of which displaces a movable wall of a fluid source, thus dispensing the fluid into the dressing to spread throughout irrespective of orientation of the dressing, maintaining a transport fluid (e.g. carrier) in the dressing and in contact with a skin defect being treated. Delivery may be periodic, constant, programmatically controlled, or manual. A dressing may maintain intimate contact, a transport fluid, and a controllable concentration of active ingredient against a skin defect. 
     Apparatus and methods to replenish a dressing with a therapeutically effective concentration of a fluid deliver a fluid carrier containing an active ingredient. The fluid may be stored in and delivered from a pump mechanism including reservoirs for a pressurization gas and the fluid, which may be loaded at a factory and sealed or filled at point of use through a valve, septum, or the like. The dressing may have a distribution network, and multiple members, dispensing the fluid into a wick maintaining a transport fluid (e.g. carrier) distributed in the dressing and in contact with a skin defect being treated. Delivery may be periodic, constant, programmatically controlled, or manual to maintain intimate contact, a transport fluid, and a controllable concentration of active ingredient against wounded tissue.

RELATED APPLICATIONS

This application is related to and claims the benefit of U.S.Provisional Patent Application Ser. No. 61/015,952 entitled“AUTO-REPLENISHING, WOUND-DRESSING APPARATUS AND METHOD” and filed onFeb. 27, 2008 for Sai Bhavarju et al., which is incorporated herein byreference.

BACKGROUND

1. The Field of the Invention

This invention relates to treatment of skin defects, and in particularto control and delivery of treatment substances to a dressing on a skindefect.

2. The Background Art

Skin defects may be inflicted by people, machines, tools, vehicles,animals, plants, the environment, and many other factors. Likewise,pressure, ailments, infections, and disease may create sores, openwounds, and other skin defects. Skin defects may be treated by a varietyof physical processes, materials, conditions, controls, and the like,each based on a particular theory, experiment, regimen, or other basisof justification. Meanwhile, skin defects may be characterized by theirsignificance or seriousness, as well as their nature, theirsusceptibility to treatment, or the like. Skin defects maybe defined aswounds, incisions, or an injury to the body (as from trauma, pathology,or surgery) that typically involves laceration or breaking of a membrane(as the skin or mucous membrane) and usually damage to underlyingtissues. Furthermore a wounds or skin defect may be characterized asminor, superficial, major, traumatic, acute, chronic, fatal, or thelike.

Skin defects may require isolation from an environment, exposure to aparticular environment, treatment by exposure to a medicament, covering,uncovering, and so forth. One area of continuing interest is thetreatment of skin defects by applying a dressing. Typically, treatmentmay include some type of anti-sepsis process. After application ofmedicament such as an antiseptic, antibiotic, or the like in tincture orointment form, a bandage or other covering may be applied to control orlimit access to the skin defects by environmental agents (e.g. air,dirt, touching, etc.).

In treating skin defects, applying a medicament may only solve part ofthe problem. Changing a dressing, replenishing a quantity orconcentration of a medicament, controlling the access, contact, andconcentration of an active ingredient applied to skin defects, andverification of the foregoing are typically difficult to do. Applicationof a constant or even reliable or consistent concentration of amedicament is difficult to accomplish, even for a regularly attendedpatient.

For example, application of a salve, ointment, cream, irrigation,tincture, or the like occurs at a point in time. The dressing itself maysoak up the medicament fluid, removing the contact with the skindefects. Drying of a carrier portion of a medicament fluid may inhibitchemical activity of an active ingredient by removing the necessarytransport fluid required for migration, diffusion, or the like. Dryingof tissues, blood, or serum may inhibit the action or effectiveness ofan active ingredient, and may even block access by an active ingredientto underlying skin defect. Thus, finding a proper delivery mechanism toconsistently, regularly, or constantly apply the right amount of atherapeutically effective active ingredient may be problematic in manyinstances.

Once a medicament fluid is applied as a salve, liquid, tincture,aspersion, cream, irrigation, or the like, the problem of theconcentration of the active ingredient may actually render theapplication ineffective relatively quickly. Many medicaments, onceapplied, have a rapidly decaying, uncontrolled, or ineffectiveconcentration. Subsequently the concentration of an active ingredient inthe bulk of a medicament fluid is necessarily much higher than theconcentration migrating to the affected skin defect area. Thus thedelivered concentration may become inappropriate. Some dressings e.g.impregnated dressings deliver either below the therapeutic range orabove it causing inadequate treatment or side effects and in the case ofantibiotics possible resistance.

Accordingly, what is needed is a method and system for consistentdelivery over time of a specific volume, specific concentration and/ortherapeutically effective concentration of an active ingredient of abeneficial fluid to the site of skin defect. Also desirable would besupplying a specific volume, specific concentration and/ortherapeutically effective concentration of a fresh active ingredient ina programmable manner to be within the therapeutic window to eliminateeffects due to under delivery or over delivery. Also desirable is amethod for maintaining a transport fluid (e.g. carrier, moisture, tissuemoisture, etc.) available to support delivery of the active ingredientto the skin defect. It would be an advance in the art to provide asystem and method to maintain a prescribed transport path, and effectiveconcentration of fresh active ingredient to the site of the skin defect.

BRIEF SUMMARY OF THE INVENTION

In accordance with the foregoing, an apparatus and method in accordancewith the invention may include a fluid delivery system that includes ahousing with reservoirs for a pressurization gas and sources for amedicament fluid. The fluid may be loaded into a reservoir at a factoryand sealed, or may be filled at the point of use through a valve,septum, or the like. Filling the device at the point of use includes theability to select from fluids containing a variety of appropriate freshactives or combinations thereof. Point of use or in situ filling has theadded advantage of separating the shelf life and handling requirementsof the device from the self life and handling requirements of theactive. This may also be referred to as In situ filling.

The system of fluid delivery may include a housing having aninextensible interior volume to contain reservoirs and fluid sources incontact with one another. A fluid source may have a wall flexible orotherwise able to move in response to pressure, being sealed to containand maintain a fluid comprising an active ingredient disposed in a fluidcarrier. An inlet port, such as a septum may provide sterile access tothe fluid source to introduce the fluid. An outlet port is provided forthe fluid source to dispense the fluid.

A reservoir containing a gas moves at least one wall in response topressure from gas output of a galvanic cell within or outside, but incommunication with the reservoir. An electric circuit may controlcurrent flow to control the rate of generation of gas. The circuit mayuse a resistor and switch, a more sophisticated control circuit, or amicroprocessor controller to control current and thus the gas generationrate. The electrical circuit may be within the reservoir or within thehousing or outside the housing. The electrical circuit may be controlledremotely or directly, by electrical, electromagnetic, magnetic, opticalor mechanical means.

An outlet dispenses the fluid from the fluid source in response todisplacement of its wall by the gas reservoir, sending the fluid througha feed conduit to a dressing. The term conduit, feed conduit, feed line,and tubing may be used interchangeably throughout this disclosure. Thefeed conduit may be as short or as long as desired, supporting placementof the pump nearby, or remote from, the dressing. The feed conduit mayinclude a restricted tube providing resistance to the fluid flow,thereby establishing back pressure within the fluid source. By selectionof appropriate tubing and flow rate, a certain value of back pressurecan be established within the fluid source.

Upon activation, the fluid delivery system may generate a gas into thegas reservoir having a movable wall. The movable wall of the gasreservoir exerts pressure and displacement against a movable wall of thefluid source or reservoir, thus displacing the fluid. It will beappreciated by those of skill in the art that the combination of thehousing, gas reservoir, and fluid source may be configured as a pump orpump mechanism. The displaced fluid may pass through a feed conduit to adressing and ultimately to a skin defect to which the dressing isapplied.

The dressing may include a distribution member which may be a wickinglayer, a manifold of tubes with apertures, or a pouch with pores thatallows the fluid to be distributed substantially uniformly irrespectiveof orientation of the dressing. In one embodiment, the distributionmember maintains a fluid in the dressing and in contact with the skindefect being treated. The fluid may be a transport fluid or carrier forconveying an active ingredient to the skin defect.

A connector positioned on the dressing connects the feed conduit to adistribution member portion of the dressing. The connector may beadvantageously positioned centrally on the dressing even though it maybe anywhere on the dressing. The distribution member may distribute thefluid there across, maintaining substantially even wetting across thedomain irrespective of orientation of the dressing. The fluid maysaturate the wicking portion, thus making the fluid available to be inintimate contact with the skin defect. The orientation independence ofthe wicking member may be accomplished by implementing various effects,including capillary action, hydrophobic/hydrophilic nature of the layer,surface tension optimization, composition, or texture and weavepatterning of the layer, or the effects of evaporation. These effectsindividually or in combination are referred to “wicking action.”

When the distribution member is a manifold, the fluid may exit the feedconduit and into a manifold and exit substantially evenly through theapertures irrespective of orientation by maintaining a high fluidpressure in the manifold relative to barometric pressure. The fluid mayalso be delivered substantially evenly through the pores in the pouchdue to the comparatively high and uniform pressure across the plenumcreated by the pouch. A specific volume, specific concentration and/ortherapeutically effective concentration, or in other words apredetermined range of concentration, of the active ingredient may thusbe available and in intimate contact with the skin defect, providing atransport fluid, active ingredient, constant rate, controllable andrenewable concentration, and intimate contact. The terms manifold,header, arms, distribution tubes, tree structure, and plenum are usedinterchangeably throughout this specification.

The dressing may function effectively with any generic source other thanthe specific pump system described herein. Therefore, the source may bemanual, such as a syringe, or any other delivery mechanism includinggravity feed, mechanical pumping etc. The source can supply fluidcontinuously, discontinuously, programmably, manually, or the like.

In one embodiment, the dressing is configured to be cut to size, andstill maintain the functional properties of the dressing. This willallow the dressing to be adaptable to the size of the skin defect.

The fluid may be configured as a liquid having an active ingredientdissolved within the liquid, or suspending as a micro-pulverizedparticulate, all disposed within a liquid having a viscosity selected tooptimize a therapeutic effect a fluid may have a viscosity ranging froma very thick, honey-like substance, to a comparatively aqueous like,such as water or other liquid base. Furthermore, a fresh active is aquality of material that remains substantially in its original state andhas not been degraded. A fresh active may also be provided in quantitiesthat need not anticipate such degradation or change in the kinetics ofdelivery. For the purposes of this disclosure the terms fluid, freshactive, and medicament may be used in similar manners discernable by oneschooled in the art. A medicament maybe a fluid or it may be in someother form.

The active ingredient may be an agent having antimicrobial, antibiotic,analgesic, anti-inflammatory, hydrating, growth promotion, enzymaticdebridement, antiseptic, irrigation, anesthetic, or emollient effect,and may be systemic, penetrating, or topical. The fluid carrier of thefluid may be a liquid, gas, gel, sol, thixotropic, colloid, or otherfluid, and may carry the active ingredient dissolved therein orsuspended as particles in suspension.

The housing may be substantially rigid and made of metal, metal alloy,polymer, reinforced polymer, ceramic, or the like. Steel, stainless,brass, bronze, aluminum, titanium, and copper as well as olefinic,styrenic, polycarbonate, and elastomeric hydrocarbons may serveadequately. The housing may be transparent to visible light, which mayprovide sight monitoring, but opacity may provide protection of theintegrity of the fluid. The housing may not be gas tight, but vented,thus allowing point of use filling of the fluid source or other actionsexpelling gas from the housing during operation.

Any reservoir or fluid source may have a pressure-relief mechanism, suchas a vent or check valve, to regulate pressure, resist backflow, preventrupture, or the like. The fluid source may be filled by a syringe,through a valve or septum, and may be overfilled in order to prime thefeed conduit, the dressing, or both prior to activation of the gasgenerator. Reservoirs or fluid sources may be permanent or replaceable,single use or refillable, or the like. Likewise, the housing may bedisposable or reusable, sealed, or openable. The gas present in thereservoir may be vented at any time. The fluid source may be pre-filledor filled at the point of use, and disposable or refillable. The pointof use capability allows the user to select the suitable treatment amongmany options and greatly extends shelf life.

Gases from the gas generator may be any of those readily generated byelectrochemical means. For example hydrogen, oxygen, nitrogen, or carbondioxide may be generated by galvanic cells without any need for externalpower. Typically, for a gas phase device with higher operating pressurecomes less sensitivity to the environment, particularly the effects ofchanges in ambient temperature and pressure are proportionately lessenedwith higher operating pressures. Greater than ambient operating pressuresubstantially improves the precision and accuracy of the deviceperformance. Significantly higher operating pressures reduce the ambienteffects substantially.

The gas generator may include a galvanic cell completely containedwithin the gas reservoir. The gas reservoir may be formed of adielectric material to further insulate the electric circuit inside. Thecircuit may be outside the reservoir or even outside the housing, butsealing may be easier if no penetrations are required in the wall orseams or the reservoir. Actuation may be direct or remote, from amechanical force, magnetic field, electric pulse, radio frequencysignal, acoustic wave, or the like. Any activity of the apparatus may beindicated by an indicator identifying an “on” condition.

The feed conduit may be formed to be substantially inextensible, or mayrespond to pressure by including a pressure accumulator or simply anelastic portion to expand to ameliorate any sudden increase in pressure

In use, an apparatus having a housing and a flexible reservoir and fluidsource may have a selected fluid introduced as a fluid, and may befilled in a manner to prime the feed conduit, dressing, or both byinjecting the fluid into the fluid source. Filling may pressurize thefluid source and force open a check valve, filling the feed conduit, andpartially filling or saturating the dressing. Filling may also result inthe initial pressurizing of the fluid source, expediting the need forthe gas bag to do so and decreasing start up time.

The distribution member may be a manifold that distributes the fluid tovarious regions of the wick portion thereof. Tubes having perforationsor orifices to resist flow may maintain a substantially equal pressureinside the distribution manifold. Sizes of path lengths, diameters,orifices, or the like may control pressure among outlets of tubes,plenums, pouches, bags, or the like to effect even distribution of thefluid.

A multi-member dressing may include a distribution member that may be awicking layer receiving the fluid, a protective member that may or maynot be configured to protect the dressing from the environment andprovide for vapor transmission, a transfer or transport member totransfer the fluid to the wicking layer, a fluid absorber to absorbexcessive fluid being delivered or for absorbing the wound exudate, atenting member positioned at the rim of the dressing to provide forlateral evaporation, and an interface member between the wicking layerand the treated skin defect to transfer the fluid thereto from thewicking layer while performing any other function needed, such asanti-adhesion, or the like. Alternatively, the dressing may comprise atleast one functional member consisting of a distribution member, andadditionally an interface member, transport member, barrier member,fluid absorber, any of said members could be integrated to achievemultiple functions in one or more members.

An interface member may be formed as a sheet, foam, gel, gauze, porousmatrix, honeycomb, mop of fibrous material, comminuted fibrous material,nanotube composite structure, or the like, or any combination thereof.The material thereof may be a biodegradable copolymer, dermalregeneration template, bioabsorbable gel, anti-adhesion polymer, skinsubstitute, moisture-retaining natural or synthetic composition,angiogenic composition, antimicrobial composition, or the like, or anycombination thereof. The carrier along with the active ingredient may bedelivered directly to the skin defect. Alternatively the active alonemay be transferred to the skin defect by diffusion or migration. Thecurrent device allows maintenance of fluid balance in the skin defectunder treatment. For example, moisture may be provided to the skindefect and excess moisture may be removed by vapor transmission or by anabsorptive member. The interface layer may also be referred to as thenon adhering layer.

The distribution member material may be a polymer sheet, woven fabric,non-woven fabric, naturally occurring fiber, sponge, fiber matrix,gauze, absorbent material, adsorbent material, gel, foam, or the like,or any combination thereof. Systems and methods in accordance with theforegoing may treat dermatological disorders, incisions or deeperwounds. For example embodiments of systems and methods in accordancewith the invention may be useful for delivering a fluid prescribed for acut, laceration, scrape, allergy eruption, skin cancer, rash, burn,undesirable growth, cyst, wart, tumor, ulcer, boil, irritation,incision, trauma or the like.

In general, a therapeutically effective concentration of an activeingredient may be delivered to the site of a disorder and delivered byintimate contact through the dressing. A pore size in a wicking portionof a dressing may be selected evenly distribute the fluid carriercontaining the active ingredient, independent from orientation.

The described apparatus for delivering fresh fluids to the skin defectsmay also be coupled with other well known wound treatments such asdebridement, negative pressure wound therapy, phototherapy, surgicaltreatments, compression therapy, tissue replacement or the like.

All the components in the described dressing have configurations thatfunction independently from their orientation. Thus, the dressing orsystem as a whole may operate independent of orientation constraints.

The system is storage stable. Due to the stability of the mechanical andchemical systems, and the empty or closed nature of the mechanicalsystems, all may be stored for an extended period of time (e.g. monthsor years) before being put to use by point of use filling of the fluidsource.

Whether delivered at a substantially constant rate, periodic dosagevolume, feedback controlled saturation or moisture content, chemicallydetectable concentration, or by manual intervention, delivery of apre-selected, therapeutically effective, threshold concentration may beprescribed. The rate may be at a threshold value or in a range. Thecontrol points for either a threshold value or a range may be selected,and the fluid delivered to effectively control pain, biotic growth,hydration, aeration, chemical reactions, biological process, or thelike, or any suitable combination thereof.

Thus a periodically, constantly, or programmatically delivered amount ofa fluid into a dressing may maintain intimate contact, a transportfluid, and a controllable concentration of fresh active ingredient to asite of skin defect. The term skin defect could be any dermatologicaldisorder such as a wound, allergy eruption, skin cancer, rash, burn,undesirable growth, cyst, wart, tumor, ulcer, boil, irritation,incision, graft, oiliness, dryness, wrinkles, blemishes, discolorations,and trauma. The term “skin defect” may be used interchangeably with anyof these terms throughout the specification, depending upon the contextin which the term is used.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing features of the present invention will become more fullyapparent from the following description and appended claims, taken inconjunction with the accompanying drawings. Understanding that thesedrawings depict only typical embodiments of the invention and are,therefore, not to be considered limiting of its scope, the inventionwill be described with additional specificity and detail through use ofthe accompanying drawings in which:

FIG. 1 is a perspective view of one embodiment of a fluid deliverysystem for delivery of a fluid to a dressing for a skin defect;

FIG. 2 is a perspective view of various alternative embodiments of apump configured for use in a fluid delivery system and method inaccordance with the invention;

FIG. 3 is a perspective view of various alternative embodiments of feedconduits for conducting a fluid from a pump in accordance with theinvention;

FIG. 4 is a perspective view of various configurations of a dressing foruse in a fluid delivery system and method in accordance with theinvention;

FIG. 5 is a perspective view of various embodiments of distributionsystems within a dressing in accordance with the invention;

FIG. 6 is a perspective view of one embodiment of a dressing in variousorientations that may be occupied during service in accordance with theinvention;

FIG. 7 is a perspective view of various members that may be consolidatedto form a dressing in accordance with the invention;

FIG. 8 is a schematic diagram of a gas generator with variousalternative embodiments on the controller therefore in accordance withthe invention;

FIG. 9 is a side plan view of a cross-section of one embodiment of ahousing and reservoir and fluid source system for a pump in accordancewith the invention; and

FIG. 10 is a perspective cutaway view of an alternative embodiment of ahousing and enclosed reservoir and fluid source in accordance with theinvention.

DETAILED PREFERRED EMBODIMENTS DESCRIPTION

It will be readily understood that the components of the presentinvention, as generally described and illustrated in the drawingsherein, could be arranged and designed in a wide variety of differentconfigurations. Thus, the following more detailed description of theparticular embodiments of the apparatus, systems, and methods inaccordance with the present invention, as represented in the drawings,is not intended to limit the scope of the invention, as claimed, but ismerely representative of various embodiments of the invention. Theillustrated embodiments will be best understood by reference to thedrawings, wherein like parts are designated by like numerals throughout,and trailing letters following a numeral simply indicate specificinstances of the item identified by the corresponding reference numeral.

Referring to FIG. 1, an apparatus 10 or system 10 in accordance with theinvention may include a pump 12 operating as a delivery mechanism 10 fora fluid. The fluid may typically be of a viscosity in a configurationsuitable for pumping. Likewise, a fluid may be configured as a liquidhaving an active ingredient dissolved within the liquid, or suspendingas a micro-pulverized particulate, all disposed within a liquid having aviscosity selected to optimize performance of the apparatus 10. Forexample, in one embodiment, the fluid or liquid operating within thepump 12 as a fluid may have a viscosity ranging from a very thick,honey-like substance, to a comparatively aqueous like viscosity, such aswater or other liquid base.

In another embodiment, the fluid may be a gel containing gelatin orother gelling agents in a liquid solution to stabilize that solutionagainst separation, evaporation, or the like. Accordingly, a medicamentor active ingredient may be dissolved in a liquid, and the liquid may bestabilized with a gelling agent.

The active ingredient may include at least one composition chosen froman antimicrobial, an antibiotic, an antifungal, an antiviral, anantiseptic, and an antibacterial agent. The active ingredient may alsoinclude at least one composition chosen from an analgesic, a palliative,and an anti-inflammatory agent. In one embodiment, the active ingredientcomprises at least one composition chosen from de-ionized water, apolymeric gel, a saline composition, and a hydrocolloid. The activeingredient may comprise at least one beneficial agent chosen from anenzymatic debrider, a tissue growth factor, a scar-reducing agent,tissue cells, topical nutrients, a coagulant, nitric oxide, oxygen gas,ozone, and a gene therapy agent. It will be appreciated by those ofskill in the art that the active ingredient may be selected to betherapeutically effective in treating a dermatological disorder chosenfrom a skin defect, an allergy eruption, a skin cancer, a rash, a burn,a growth, a cyst, a wart, a tumor, an ulcer, a boil, an incision, agraft, oiliness, dryness, wrinkles, blemishes, discolorations, trauma,and numerous other maladies or conditions.

In general, an apparatus or fluid delivery system 10 may operate todeliver a fluid through a feed conduit 14 extending a distanceappropriate to service a dressing 16. In certain embodiments, the fluiddelivery system 10 may include a housing 18. The housing 18 may be madeof any suitable material and manufacturing method. For example, variouspolymers may be formed by methods such as vacuum forming, injectionmolding, blow molding, casting, or the like in various suitable shapesto have an interior cavity of suitable shape.

The housing 18 may be made in one or more parts. For example, thehousing 18 may be opened like a clam shell. Alternatively, the housing18 may be formed as a single piece. In other embodiments, the housing 18may be formed as a single piece having hinge portions and latch portionsin order to close the housing 18 portions upon themselves in order toenclose the contents thereof.

The housing 18 may be formed as pieces, fabricated and assembled to bepermanently closed. The housing 18 may also be manufactured by stamping,die casting, centrifugal casting, investment casting, or other methodsused in forming polymers or metals.

The housing 18 may be formed to have an opaque appearance on one or bothsides or halves, or may have a translucent or even transparentappearance. In a transparent configuration, the housing 18 may providevisibility of a fluid therein. Thus, a quick, visual inspection mayprovide feedback on whether the amount or condition of the fluid issuitable. Likewise, any malfunction or abnormality of operation of thepump 12 may be readily visible within the housing 18.

Polymer resins for injection molding may provide a comparativelylightweight and rigid structure for the housing 18. Likewise, however,various stamped or die cast metal parts may also provide a robust,rigid, strong housing 18 for containing pressurized fluids incontainers. For convenience, having a comparatively small aspect ratioof thickness to length or of thickness to height, in housing 18, maybenefit from a comparatively thicker wall.

Nevertheless, if a sufficiently light and strong material andconstruction configuration are used for the housing 18, an aspect rationear unity may be appropriate as containment. For example, a hard, rigidhousing 18 may provide protection against rupture or failure under theinfluence of accidental over-pressurization. This may be important inpreventing an accidental bolus from being delivered due to crushing orcompression of a compressible container within a compressible housing18.

Nevertheless, such a safety or control issue may not be a problem when ahousing 18 is connected by a clip or magnet to a bed frame, medical IVstand, or the like. Then, a simple containment vessel of a sack type orwire frame type may suitably act as a housing 18. On the other hand, ahousing 18 may be exposed to pressure by being placed on the bed orunder the pillow of a patient or in a pocket of the clothing worn by apatient. Then, the dynamics may dictate the necessity of a rigid housing18 capable of withstanding external pressures.

In the illustrated embodiment, a gas generator 20 may provide anintegrated source of gas to fill a reservoir 22. For example, the gasgenerator 20 may include an electrochemical cell. In one embodiment, thefluid delivery system 10 includes a galvanic cell in communication withthe reservoir and comprising a chemical selected to produce a gas withinthe reservoir 22. Thus, a galvanic cell, in which a galvanic reactionoccurs generating gas as a byproduct of the chemical reaction, is asuitable mechanism for a gas generator 20. In such embodiments, acontrol circuit may be an integrated portion of the gas generator.

In certain embodiments the gas generator 20 may be enclosed completelywith the reservoir 22, thus easing the need for complex or unreliablesealing procedures and materials. That is, sealing different materialsor hard materials to flexible materials, or the like may sometimes beproblematic. Likewise, over time, seals may deteriorate, separate, orotherwise fail.

By contrast, if the gas generator 20 is integrated within anelectrochemical cell, but then completely encapsulated within thereservoir 22, a switch or controller may be imbedded. Access may beobtained by applying pressure to the switch or controller through thewall of the reservoir 22, by pushing on it through an opening in thewall of the housing 18. In such a manner, control of the gas generator20 may be exercised within a sealed system of the reservoir 22.Alternatively, a switch mounted to a circuit board is sealedcontiguously onto the face of the reservoir 22 in such a manner tomaintain the gas tight property of the reservoir 22. In certainembodiments the galvanic cell is enclosed in the reservoir 22 and thewires from the cell where connected to the circuit board positioned onthe housing 18 wall allowing easy access to the circuit board.

An electrical conductor having various elements of control may run thegalvanic cell to complete the circuit between the two reactantmaterials. A controller may be connected to the galvanic cell in acircuit to control the generation of the gas in the reservoir 22,thereby controlling a delivery rate of the fluid from the fluid source.The controller may comprise a fixed or variable resistor and a switch.Control may be exercised by something as simple as a resistor on aswitch or something as sophisticated as a microprocessor-controlledcircuit operating based on a sophisticated, programmed application. Forexample, the controller may include a processor programmaticallycontrolling the value of resistance in the circuit. The fluid deliverysystem 10 may also include a sensor (not shown) operably connected toprovide inputs to the processor to control the value of resistance inaccordance with an algorithm therewith.

In one embodiment of the fluid delivery system 10 at least a portion ofthe controller is located separately from the galvanic cell and is incommunication with the cell by at least one of mechanical hardware,electromagnetic, radio frequency, magnetic, or optical feedback orcircuit. In other embodiments, the controller is located inside thereservoir 22.

In operation, the gas generator 20 acts to fill the reservoir 22 in acontrolled manner. Accordingly, the reservoir 22 will expand with thevolume and pressure of the gas generated by the gas generator 20.Accordingly, the reservoir 22, contained on one side by a shell 24 orhalf 24 of the housing 18, may expand to displace the fluid source 26.The fluid source 26 in contact with the reservoir 22 is thus compressedbetween the reservoir 22 and a wall of the housing 18, resulting inexpression of the fluid. Accordingly, the housing 18, together with thereservoir 22 and the fluid source 26 may be referred to throughout thespecification as a pump 12.

The fluid source 26 within its shell 28 or half 28 of the housing 18 mayactually contain any type of fluid. In one example, gas, liquid, or gelof suitable consistency and chemical composition may dispense from thefluid source 26.

In certain embodiments, a fluid may be loaded in the fluid source 26 ata manufacturing plant. The fluid source 26 may there be sealed tomaintain a sterile condition until use. In an alternative embodiment,the fluid source 26 may be filled on site or at point of use by adoctor, pharmacist, or other medical professional responsible.

Either factory filling or onsite filling may use a fill port 30. Costand security for a pre-filled fluid source 26 may militate againsthaving a fill port 30. However, for a fluid source 26 designed to befilled or at point of use, a fill port 30 may be provided with an access32 or inlet fixture 32. In one embodiment, the access 32 may be a septum32 through which a syringe may penetrate to fill the fluid source 26.The fill port 30 may be made of a material of sufficient hardness andlength to receive a needle without risk of puncture. The fill port ormay alternatively be a luer lock type.

The fluid source 26 may be formed of any material that will contain theliquid but not actively affect the contained fluid, for example,polyethyleneteraphthalate (PET). In certain embodiments, various otherpolymers such a polyethylene, polypropylene, polyvinylchloride, or thelike may be suitable. However, in general, the nature of the material ofthe fluid source 26 should not admit any harmful substances or reactionsto the contained fluid.

This is particularly important for situations where the fluid source 26may sit on a shelf, filled with a fluid, for a considerable period oftime. For example, in a factor-sealed fluid source 26, the shelf life ofthe fluid must be configured along with the shelf life of the chemicalconstituents, plasticizers, and other chemicals that may be leached fromthe wall of the fluid source 26 into the fluid of the fluid.

In one embodiment of a method and apparatus in accordance with theinvention, a medical professional may draw a fluid into a syringe. Thesyringe may be fitted to a needle or other injector to penetrate theseptum 32 or access 32 to the fill port 30. A suitable amount andconcentration of a prescribed fluid may fill the fluid source 26 to asuitable level required to service the dressing 16 for a predeterminedtime.

The volume added to the fluid source 26 may completely fill the fluidsource 26. Alternatively, the amount of the fluid added to the fluidsource 26 may exceed the capacity thereof. For example, the apparatus 10may be “jump started” by adding a bolus of fluid to fill the fluidsource 26, the feed conduit 14, and some portion or all of the dressing16. Thus, the dressing 16 may be pre-loaded or even pre-saturated by afluid when first loaded. Repeated boluses are possible.

Likewise, in certain embodiments, the apparatus 10 may be filled by anindividual patient. For example, many superficial wounds such as scrapesand lacerations may benefit from an over-the-counter (OTC) solution,salve, oil, antiseptic, antibiotic or the like. Accordingly, an OTCversion of the apparatus 10 may be either pre-filled or filled by a userwith an OTC fluid.

In service, the apparatus 10 may feed a fluid from the fluid source 26out through an exit port 34. The exit port 34 may be provided with afitting 36 adapted to accomplish one or several functions. For example,the fitting 36 may include a check valve to prevent any back flow of thefluid from the feed conduit 14 into the fluid source 26. Likewise, thefitting 36 may include an orifice or other metering device to limit theflow of fluid to a particular rate.

A regulator, check valve, or pressure-relief valve may be part of thefitting 36 to maintain a certain pressure within the fluid source 26.The regulator may be outside of, partially within, or completely withinthe fluid source 26. Pressure in the fluid source 26 may be particularlyimportant to precise control of delivery. It may need to increase whenoperating with particular fluids. Perhaps most frequently, regulation ofpressure may resist wide fluctuations in the rate of delivery of thefluid.

For example, barometric pressure, ambient temperature, and the like maydirectly affect the pressure of gas in the reservoir 22. Widefluctuations in either may be counter-productive to precise metering ofa fluid through the fitting 36. If a pressure-regulation valve islocated within the fitting 36, or otherwise associated therewith,comparatively higher pressure reduces sensitivity of the fluid source 26or reservoir 22 to ambient pressure and temperature. For example, abolus dose is not administered simply as a result of an increase inambient temperature increasing the volume of the gas in the reservoir22.

Thus, in one embodiment, the fluid source controls a fluid flow todressing 16 or to a distribution member 40. The flow rate may becontinuous or discontinuous. A discontinuous flow rate may be one thatturns off and on over a period of time. A discontinuous flow rate mayalso be one provided under the variable force of a syringe. In oneembodiment, flow rate may be programmatically controlled by acontroller. The program may account for fluid flow patterns, eitherpre-selected or arbitrary, valve, conduit size, and other flow controlparameters.

In general, an aperture 38 in either shell 24 of the housing 18 mayprovide access to a button to control operation of the gas generator 20.The aperture 38 may be closed with a cover, seal, diaphragm, or thelike. For example, a rubber cover may fit within the aperture 38resisting entry of dirt, dust, moisture, and the like into the housing18. Nevertheless, a cover of thin, flexible, elastomeric material allowsa user to apply pressure to a control button of the gas generator 20.

In certain embodiments of an apparatus and method in accordance with theinvention, a cover member 39 or protective member 39 of a dressing 16may provide one or more useful functions. For example, the protectivemember 39 may be opaque in order to prevent unsightly appearance of thedressing 16. By the same token, the protective member 39 may betransparent in order to provide easy monitoring. One may observedirection the distribution of the fluid throughout the dressing 16, aswell as any seeping of blood or serum back into the dressing 16 from askin defect being treated.

Likewise, a protective member 39 may typically resist abrasion,snagging, and other contact or contamination damage to itself and theunderlying distribution member 40. Other members may exist within adressing 16. Nevertheless, a protective member 39 may resist abrasion,transport of fluid, dirt, puncture, or the like. Likewise, theprotective member 39 may be perforated or porous to permit access of airto a dressing 16.

The protective member 39 may be liquid proof to prevent escape orwicking of a fluid or other liquid in the dressing 16 into clothing,bedding, or the like. In certain embodiments, the protective member 39may be microperforated or formed of some suitable material that permitspassage of oxygen, water vapor or other gases while resisting passage ofliquids.

Typically, a distribution member 40 holds a fluid delivered from thefluid source 26 through the feed conduit 14. The porosity of thedistribution member 40 provides distribution of comparatively aqueouslike fluids throughout. Meanwhile, the generation of gas from the gasgenerator 20 into the reservoir 22 applies both pressure and volumevariation into the fluid source 26, driving a flow of fluid at somedesired, engineered rate into the dressing 16. Thus, the fluid sourcemay control the fluid flow to the distribution member 40. In oneembodiment, the feed conduit 14 is connected to the fluid source 26 forreplenishing the fluid in the distribution member 40, with or withoutadditional human intervention.

The housing 18 may be relieved at selected locations to form, forexample cradles 42, 44 capturing the fill port 30 and exit port 34,respectively. The cradles 42, 44 thus permit location of the access(inlet) fitting 32 and outlet fitting 36 outside the housing 18. Thefitting 36 may be adapted to fit into or around the feed conduit 14.

The feed conduit 14 may feed into a feed line 48 passing into thedressing 16. An inlet port 50 the center of the area of the dressing 16may distribute the fluid throughout by capillary action the distributionmember 40 of the dressing 16. In certain embodiments, a manifold (notshown) may be used. Without a tailored capillary capability in thedistribution member 40, distribution of a fluid throughout the dressing16 may be enhanced by distributing throughout the distribution member 40through a manifold. The manifold may be configured in any suitablemanner. It will be appreciated by those of skill in the art that thefeed conduit may be part of the dressing 16 itself.

For example, a large plenum having substantial area or a long linearpath may present little resistance to flow of the fluid. A largerpressure drop would then occur as the fluid exits through perforationsor other flow-limiting orifices. Alternatively, a manifold may haveapertures sized to control or balance out pressure along several pathsof distribution through tubes within the manifold. These apertures mayprovide the major, substantial, pressure drop between the pressureupstream of the manifold, and the ambient pressure in the dressing 16.

Referring to FIG. 2, various embodiments of the housing 18 maycapitalize on manufacturing methods, optimization of costs, ease ofmanufacturing, simplicity of operation, weight, shape, or the like. Forexample, the housing 18 a provides an aspect ratio of thickness to widthor thickness to height sufficiently small to fit readily into a pocket.Thus, an active outpatient, wearing of a dressing 16 may remain active.A comparatively thin, unobtrusive, housing 18 a fits easily into apocket of any article of clothing.

Likewise, the housing 18 b may have a lightweight, clam shellconfiguration. A lattice 54 sufficient to contain the reservoir 22 andfluid source 26 may not provide puncture proofing for reservoir 22 andfluid source 26. However, if puncture is not a practical threat to theintegrity of an apparatus 10, the lattice 54 may provide an appropriatewall. The housing 18 b reservoir 22 and fluid source 26 are not shown,for clarity, but may fit the gas generator 20 and the inlet fitting 32and outlet fitting as with the housing 18 a.

Each of the housings 18 may be made of suitable size to match theadministration of a fluid, ease of use, and carriage needs. For example,a comparatively thinner housing 18 may operate best when the reservoir22 and fluid source 26 are placed side by side. If the reservoir 22 andfluid source 26 are placed end to end as in the housing 18 c, then theaspect ratio of width to thickness at one end 56 of the housing 18 c maybe closer to one. The length of the housing 18 c may be selected topromote complete expansion of the reservoir 22 and fluid source 26. Thegas generator 20 filling the reservoir 22 may have a button on the outerwall of the housing 18 c, or on one end 56. Alternatively, access to thegas generator button may be on the same end of the housing 18 c as theinlet fitting 32 and outlet fitting 36.

In all the embodiments illustrated, the inlet fitting 32 is optional,depending upon whether a fluid is pre-loaded and sealed into a fluidsource 26 by a manufacturer. If the fluid source 26 is filled orrefilled at the point of use some access fitting 32 is required.However, the housing may be refillable with a pre-filled, sealedreservoir 22 and fluid source 26 in some embodiments.

The housing 18 d may have a rounded, oblong cross section, an oval crosssection, or a circular cross section. One benefit of a right circularcylinder shape is minimizing the overall dimensions of the housing 18 d.Greater volume requires less surface area material if shaped like asphere. Other shapes are improved as all the aspect ratios of thickness,to width, to length approach unity. Thus, a sphere is capable of holdingthe maximum volume with the minimum area of wall. Likewise, a rightcircular cylinder provides a better or greater volume per unit of areaof wall then does a rectangular container. Nevertheless, variousconsiderations, including convenience, mobility, and the like may beused to determine what shape, aspect ratios, and materials may be usedin each of the housings 18.

In certain embodiments, the housing 18 e may be formed of one or morelightweight materials and may even be flexible. For example, the housing18 e may actually be formed of a sparse lattice work of a polymer orfiber-reinforced polymer to sustain only internal pressure, not externalpressure. Alternatively, the housing 18 e may be formed as afilament-wound composite material of resin and reinforcing fibers havingcomparatively (compared to volume changes of liquid with ambienttemperature, for example) very rigid walls in tension and compression,even sustaining very high pressures of many atmospheres.

For example, in certain embodiments, the exit port 34 may include afitting 36 containing a tiny orifice sized to meter flow of a fluid. Thehousing 18 e may sustain pressures of several atmospheres. At higheroperating pressures than atmospheric, the effects of barometric or otherenvironmental pressures and temperatures are significantly reduced. Thehousing 18 e may have aspect ratios of a pocket pen, or small pocketaccessory. A retainer 58 or clip 58 may secure the housing 18 e to apocket, clothing, bedding, or other suitable location. Engineeredselection of aspect ratios of diameter to length for any housing 18 maypromote unobtrusive location in clothing, bedding, or the like.Reliability of sealing and operation of the reservoir 22 and fluidsource 26 has advantages with circular seals.

The housing 18 f has an advantage of providing no substantial cornersand a comparatively small aspect ratio of thickness to diameter,suitable for carrying in a purse, pocket, or the like. Meanwhile,manufacturing of the reservoir 22 and fluid source 26 may be simplified,and sealing thereof readily adaptable to various manufacturingprocesses.

Referring to FIG. 3, a feed conduit 14 may optimize any parameteraffecting cost, deployment, operation, durability, reliability, or thelike. In the illustrated embodiments of FIG. 3, feed conduits 14 mayhave a round, or comparatively flat aspect. For example, the feedconduit 14 a may include a very inexpensive bottom layer 62 and toplayer 64 sealed together along a flange portion 66. The interior 60 ofthe feed conduit a may be completely empty, forming a tube. The feedconduit 14 a may be formed of plastic film, plastic-coated paper,foil-coated plastic, or the like. Accordingly, the feed conduit 14 a maybe provided in a roll.

Alternatively, the feed conduit 14 a may be cut to length or havefittings on either end preformed to interface with the outlet fitting 36and the feed line 48 of a dressing 16. A fixture adapted to the outletfitting 36 or feed line 48 may speed handling, connection, and sealing.In yet another alternative, the fluid source 26, feed conduit 14, anddressing 16 may be formed as an integrated, connected unit fordisposable use. For example, polymer-coated paper may serve thestructural and protective functions of all three components.

In one embodiment the feed conduit 14 may be filled with a core 60 orthe like. For example, the cross-sectional area compared to the lengthof the feed conduit 14 a may be extremely small. The flanges 66 may moreeasily sustain internal pressure, if enclosed volume is minimized withinthe feed conduit 14 a. This corresponds to a filled cross section thatis round or square and relatively small.

A core 60 may provide wicking from the outlet fitting 36 to the dressing16 for several reasons. For example, in certain embodiments, pressuredrop through the length of a feed conduit 14 may be desirable. Byproviding a rather tortuous path in a core 60, pressure in the fluidsource 26 is not the direct driving force for transport. Rather,evaporation in the dressing 16 may draw the fluid by capillary action,replenishing liquids. Thus, the core 60 may provide regulation andreplenishment automatically as needed.

Evaporation of liquid from a dressing 16 may provide a means ofreplenishment of the active suspended or dissolved therein. Thus, oneway to assure an adequate concentration of an active ingredient in thefluid in the dressing 16 is to provide a comparatively volatile liquidthat will evaporate from a dressing 16. Accordingly, as the carrierliquid evaporates, the fresh fluid is drawn in, having the concentrationavailable from the fluid source 26.

In certain embodiments, the entire dressing 16, feed conduit 14, andfluid source 26 may be embodied in a single integrated system 70. Forexample, the volume 68 a may be directly formed or sealed at a factoryas a fluid source 26 to be placed in the housing 18 with the feedconduit 14 b protruding there from. The feed conduit 14 b may thenconduct the fluid toward a header 50 or manifold 50 servicing a dressing16 embodied as the distribution member 68 b. It will be appreciated bythose of skill in the art that the distribution member 68 b may bedesigned or have the same characteristics as the distribution member 40discussed above. The entire system can be sealed at a factory, andfilled at point of use, or filled at the factory.

If filled at the factory, a seal may be required to close the reservoir68 a against leakage into the feed conduit 14 b. If filled at point ofuse, the entire assembly may be shipped dry. The disposable fluid source26, 68 a may be filled at point of use including optionally priming boththe feed conduit 14 b and the distribution member 68 b of the dressing16, as desired. The end 68 b may be an entire dressing assembly 16,including a distribution member 40.

The feed conduit 14 b illustrates one embodiment in which the feedconduit 14 may be rolled flat. The entire assembly 70 may be rolled flattogether or rolled together about the distribution member 40, 68 b ordressing 16, 68 b. The feed conduit 14 b may be formed of any suitablematerial, whether paper, film, foil, other laminates, or the like.Meanwhile, in the illustrated embodiments, the feed conduit 14 b may behave an integrated distribution member 68 b or dressing 68 b. Thedistribution member 68 b may be fed directly by the feed conduit 14 b,or by the feed conduit 14 b through a manifold 50. Likewise, thedistribution member 68 b may be the same as a wicking layer 14 of adressing.

For example, in certain embodiments, the dressing 16 may be formed flatof plastic film, plastic-backed paper, foil-lined paper, or foiledplastic. The distribution member 40, 68 b or perhaps the entire dressing16, 68 b, may be formed integrally at manufacture with the feed conduit14 b. When the dressing 16, 68 b is packaged, it may be sealed up andmaintained sterile along with its entire feed conduit 14 b.

If an integrated dressing 70 is formed to include the fluid source 26,68 a, distribution member 40, 68 b and intervening feed conduit 14 b,deployment may be simplified. Upon deployment, no sealing or connectionis needed between the fluid source 26, 68 a, feed conduit 14 b, and thedistribution member 40, 68 b or dressing 16, 68 b.

Fittings may be adapted to the feed conduit 14 b to readily connect ormay be unnecessary by forming all as a single containment. Upon opening,the integrated system 70 provides a fluid source 26, 68 a fitting withinthe housing 18, a feed conduit 14 b exiting through an appropriatecradle 44, and a distribution member 40, 68 b or dressing 16, 68 b atthe opposite end.

A simply activated or rupturable seal may secure the fluid source 26against any transfer of fluid to the feed conduit 14 b prior toapplication. In one embodiment, the outlet fitting 36 may be combinedwith the access fitting 32. For example, injection through a septum 32may provide piercing of a plastic seal to the fluid source 26 in orderto permit filling, or simply to permit emptying. Thus, whetherpre-filled or filled at point of use, the fluid source 26 may beconnected to the feed conduit 14 b as an integrated assembly relyingonly on the housing 18 and gas fluid source 22 supplied also at point ofuse.

In certain embodiments, tubing 14 c may provide a feed conduit. Suchtubing may be provided on a reel 69 in bulk, or in a coil suitable forimplementation as a plumbing project at point of use. In certainembodiments, the fitting 36 may easily be connected to a feed conduit 14c formed of a polymer or elastomer suitable to form a sealed, snug fitwith the fitting 36. Likewise, the feed line 48 may provide sufficientstructural stiffness, elasticity, or both to receive a feed conduit 14 csnugly fitted there around.

The feed conduit 14 d may be formed as flat tubing formed of a plasticfilm, elastomeric material, treated paper, plastic film reinforced bypaper, or the like. In the illustrated embodiment, the feed conduit 14 dmay be provided with tips 72 or fittings 72 to act as seals, and asspreaders to open the feed conduit 14 d. The fittings 72 supportconnection of the feed conduit 14 d to the fitting 36 of the pump 12, aswell as to the feed line 48 of the dressing 16. A predetermined lengthof feed conduit 14 d may minimize cost and still maintain reliablesealing between the feed conduit 14 d and its associated fitting 72 a,72 b. The fittings 72 may provide a very low cost solution to deliveryof fluid from the fitting 36 to the dressing 16.

Referring to FIG. 4, the geometry of a dressing 16 may be configured forgeneric or specialty purposes. For example, in certain embodiments, adressing 16 a may be formed in a cylindrical configuration. A bulkyshape may be required to fit within a wound that must heal itselfclosed, rather than be sutured closed.

In accordance with certain aspects of the invention, various layers 76,77, 78 may provide differing benefits. For example, an interface member78 may be provided as a non-adhering layer. For example, under the brandname TELFA™ a micro-perforated non-adhering polymer film is used inbandages. A TELFA™ layer may be appropriate for the interface member 78.In one embodiment, the interface member 78 is or contains a non-adheringpolymer. In another embodiment, the interface member 78 may be orcontain a bioabsorbable polymer. In one embodiment, the interface member78 includes one or more of the following structures, either alone or incombination: a sheet, foam, a gel, gauze, a porous matrix, a honeycomb,a mop of fibrous material, a comminuted fibrous material, and a tubularstructure. It will be appreciated by those of skill in the art that theinterface member 78 may be made of other materials known not to adhereto a skin defect.

In one embodiment, the interface member 78 is a self-destructivematerial that can peel away from an adjacent layer or member, such asthe distribution member, when the dressing 16 is removed from the skindefect and be left behind on the skin defect. For example, in oneembodiment, a gel may control adhesion and self-destruct to preventadhesion, so long as properly hydrated by the fluid. In otherembodiments, the interface may be dissolvable or absorbable over time.The interface member 78 may also be configured to separate from the skindefect when the dressing is removed.

Meanwhile, the distribution member may comprise a “smaller pore size”wicking layer 77 that may distribute a fluid to skin defect through orwithout an interface member 78 and a “larger pore size” an inner layer76 that may transport fluid by capillary action also, but with lessresistance to flow. Nevertheless, the higher effective distance (largerpore size) across porosity in an inner layer 76 may provide lessorientation-independence.

Likewise, a difference in pore size provides a net draw of liquids fromareas of larger pore size to areas of smaller pore size. Thus, an innerlayer 76 may receive a fluid from the feed line 48 a. Accordingly, theinner layer 76 may distribute readily the fluid to the principal wickinglayer 77. The principal wicking layer 77 may assure even distributionthereof.

Likewise, the dressing 16 b may be configured geometrically to fit anyparticular application. Typically, wounds that are not of a serious orpersistent nature may be closed by suturing. By contrast, chronicwounds, and wounds that may be subject to infection may be allowed orrequired to heal themselves closed, or may be closed only afterinfection has been eliminated or sufficiently reduced. Accordingly, adressing 16 b may be formed to fit within an open wound, thus deliveringfluid by contact against the deep, affected, open surfaces of the wound.

The manufacture of the dressing 16 b may begin with a cylinder, such asthe layered cylinder of the dressing 16 a. The cylinder 16 a may then bemolded, embedded with holding agents, stitched, heat set, or otherwiseshaped as desired. Accordingly, the features of the dressing 16 a may beimplemented in a dressing of the configuration of the dressing 16 billustrated. Many specialty shapes may be made in this way to fitspecific needs.

Many dressings are applied to surfaces covering and surrounding skindefects or wounds. For example, an injury may cause an open cut,laceration, scrape, burn, or the like. Likewise, an incision may leave awound to be healed. In other circumstances, sores, boils, or the likemay result in an open wound. The wound itself may need access to afluid, but the surrounding area may also need a different treatment.

The area of a dressing 16 c may be subdivided into regions. For example,a central region may contain the wound, and a surrounding area may beclear. In certain embodiments, two separate feed lines 48 c may beprovided to address two separate areas of a dressing. For example, if awound itself needs an antibiotic, but a surrounding area needs anantiseptic, both may be delivered to different portions of a dressing 16c or two different dressings 16 c.

In certain embodiments, a dressing 16 c may receive a fluid through afeed line 48 c into a plenum 82. The plenum 82 may act as a manifold 50feeding various runs 84 or arms 84 distributing a fluid to the fartherreaches of the dressing 16 c. In the illustrated embodiment, theprotective member 39 is shown as transparent in order to view the plenum82 and runs 84.

As discussed hereinabove, the protective member 39 may be opaque,transparent, thin, thick, or otherwise configured to accomplish itsfunction. Functions may typically be selected from preventingevaporation, promoting evaporation, providing resistance to abrasion,puncture, or other damage, providing access to air, providing protectionfrom air, and so forth.

In the arms 84 or runs 84 off the plenum 82, perforations or otherapertures may be selectively distributed. In certain embodiments, theentire network 80 may be porous yet resistant to leakage. For example,each of the plenum 82 and the runs 84 may be full of liquid dispensedonly slowly and evenly throughout the dressing 16 c via microporesdriven only by pressure from the fluid source 26.

In other embodiments, the plenum 82 and arms 84 may actually bedistribution tubes sized to receive and pass a liquid or other fluidreadily, yet be sealed along their entire lengths except for an apertureat the end thereof. In certain embodiments, a dendritic or branchingstructure of the arms 84 may take on any suitable shape, whetherrectangular, triangular, circular, polygonal, repeated bifurcating, orthe like, and may branch sequentially any number of times.

For example, in certain embodiments, a tree structure may have a trunkor plenum 82, in which the branches 84 or arms 84 branch from oneanother, thus providing a network of distribution tubes. In certainembodiments, ends of the arms 84 may be drawn down or restricted in someother way in order to equalize pressure throughout, and provide controland distribution at an even rate throughout all of the end points ortips of the arms 84 throughout the dressing 16 c. The distributionmember 40 is then responsible to distribute from the arms 84 throughoutitself in order to maintain a distribution of the fluid.

In general, the dressing 16 d may include a protective member 39, adistribution member 40, and any other members need for distribution,promotion of flow, protection from outside environmental influences,protection against adhesion with the skin defect, or the like.Meanwhile, after penetration by the feed line 48 d, the distributionsystem within the dressing 16 d may take on any suitable form, such asthose illustrated in FIG. 5.

Referring to FIG. 5, various embodiments of a dressing are illustrated.For example, the dressing 16 e may actually contain a distributionmember with a layer fed by a manifold 50 contiguous and continuous witha core 60 of a feed conduit 14. For example, the feed conduit 14 a ofFIG. 3 provided an upper layer 64 and base layer 62 sealed to form afeed conduit there between. Either a cavity or passage may be providedor a wicking core 60.

In certain embodiments, a dressing 16 f may be formed with a membrane 86forming either a protective member, or a pocket. In certain embodiments,the membrane 86 may be formed as an envelope having distributionopenings on the underside thereof against the distribution member 40 ofa dressing 16 f. For example, the feed line 48 may feed into apocket-like membrane 86 having porosity only around the underside edgesthereof. Likewise, the edges themselves may simply be perforated withsmall perforations tending to render the membrane 86 a large plenum.

The membrane 86 or membrane pocket 86 may be tacked through at certainlocation across its area, in order to prevent it from inflating inresponse to the pressure and presence of a fluid therein. Likewise,suitable perforations or other porosity may be sized and distributedacross its underside, around its periphery, or along the perimeter ofits underside in order to deliver a fluid into the underlying dressing16 f, or into the distribution member 40 of the dressing 16 f.

The dressing 16 g may include a protective member 39, and an underlyinginterface member 88. Between the protective member 39 and the interfacemember 88 may be a wicking material suitable for the function.Meanwhile, the feed conduit 14 may feed into the dressing 16 g while thedressing itself passes fluid through the microporosity of the interfacemember 88.

In an alternative embodiment, for which the dressing 16 g may also serveas an illustration, the protective member 39 of the dressing 16 g may bethe wick portion, while the interface member 88 serves as a plenumhaving a distribution of perforations to feed the fluid into theprotective member 39. In accordance with the invention, a feed conduit14 may feed into the interface member 88 formed as a hollow, flat, tubeperforated to feed a protective member 39 which may be the wicking layerin this embodiment associated with the dressing 16 g. In such anembodiment, a closed, flat, tubular membrane 88 may be perforated on oneor both sides to feed into a distribution member 40. Thus, rapiddistribution occurs along the comparatively larger volume available inflat tube 88. The tube 88 acts as a plenum 88, providing the fluid tothe perforations crossing into the wicking layer, here represented by aprotective member 39. Other members may be present in addition for otherfunctionality as discussed hereinabove.

The dressing 16 h formed of a wicking material such as a fiber, fabric,gauze, foam, or other material may be used alone. Alternatively, it maybe used to assemble a dressing. In yet another embodiment, it may belocated inside other members, such as between a barrier member and anon-stick member shown in FIG. 7. Accordingly, a full-width manifold 50may provide an even distribution from an edge of a distribution member40. The distribution member 40 may be engineered to standard or customshapes, areas, thicknesses, widths, and lengths to meet the flow demandsof a fluid to a particular skin defect. Sizes and shapes may includecircular, rectangular, or cut-to-order for particular injured areas. Inone embodiment, the distribution member 40 is configured to be cut to adesired size and still maintain a substantially uniform volume of fluidacross the distribution member 40. Accordingly, in one embodiment, across-section of the distribution member is substantially the same andany other cross-section of the distribution member. It will beappreciated by those of skill in the art that multiple layers or membersof the dressing 16 may cut individually or collectively to customize thesize of the dressing 16.

In one embodiment, a dressing 16 j may feed a distribution member (notshown) opposite a protective member 39. For example, a distributionsystem 80 or distribution tubes 80 may include a plenum portion 82 aswell as various arms 84. In the dressing 16 j, the plenum 82 or even theentire distribution network 80 may be formed of two layers of film. Theside of the film fitted against the distribution member may havemicroperforations 90 sized to provide an even distribution.

The placement, size, and number of the perforations 90 may control thepressure drop from within the plenum portion 82 into the distributionmember 40. Typically, however, the pressure differentials between theplenum portion 82, and the inside of the arms 84 may be comparativelyquite small compared to the pressure difference between a fluid source26 and a plenum 82. Accordingly, the distribution pattern of theperforations 90 may provide a limited number of outlets to controldistribution into a distribution member 40.

In certain embodiments, a dressing 16k may have spiraling distributiontubes 80. For example, the distribution tubes 80 may be perforated alongits entire path. The distribution tubes 80 may be configured as a spiralhaving a continuously decreasing cross-sectional area. Alternatively,the size of the internal diameter of the distribution tubes 80 may beconstant, but the perforations may be comparatively smaller. Thus, thedistribution tubes 80 become a plenum feeding out the fluid into thedistribution member 40.

The distribution tubes 80 may have branches extending from the spiral.On the other hand, manufacturing may dictate a very simpleconfiguration. Accordingly, a constant diameter and regular perforationsof suitable size and distributed along its continuous length may operateadequately. Sealing one end of a perforated tubing, with the oppositeend serving as a feed line 48 may provide a completely serviceabledistribution tubes 80.

In certain embodiments, a dressing 16 m may have a serpentinedistribution tubes 80. Again, the serpentine shape may be formed ofcommercially available tubing, flat tubing, a pocket between layers offilm or other material, or the like. Pressure drops may be engineeredfrom the pressure of the gas in the reservoir 22 through to the pressurein the fluid source 26 holding the fluid, on to pressure drops throughthe exit port 34 and fitting 36 as well as the feed conduit 14.Meanwhile, the pressure dropped from the feed conduit 14 into anymanifold 50 or distribution tubes 80 and on to the ambient environmentof a dressing 16 may be engineered to make uniform the distribution inthe illustrated embodiments.

One benefit of an engineered distribution member 40 of suitably smallpore size is an independence from the effects of orientation. Forexample, in many circumstances, a dressing is assumed to liehorizontally. Accordingly, in theory, the entire dressing is at an evenheight. Thus, gravity effects do not alter dramatically the distributionof a fluid there throughout. Accordingly, the force exerted on the fluidby wicking action would be greater than or equal to the force exerted onthe fluid by gravity.

However, in reality, many patients have skin defects located on verticalsurfaces. For example, an outpatient may actually be active, walkingabout, engaging in athletic activities, while having a dressing 16 inplace on an arm, leg, foot, torso, or the like. The effect of gravity isto bring a liquid down to the lowest contained altitude possible.However, by selecting the pore size, composition, construction, therebycreating specific hydrophobic/hydrophilic interactions, surface tensionaffect, or capillary force affect of the distribution member 40 anapparatus and method in accordance with the invention may provideindependence of orientation.

Referring to FIG. 6, a dressing 16 may comprise a feed conduit (as shownand described in connection with FIGS. 1, 3, and 5 above) for deliveringa fluid to a distribution member. The dressing 16 m 16 p, 16 q, and 16 rand distribution member receive and distribute the fluid substantiallyuniformly across the distribution member, irrespective of theorientation of the distribution member. The term “substantiallyuniformly” in relation to fluid distributed across the distributionmember may mean that fluid is distributed to all parts of thedistribution member 16. This may occur across a particular layer of thedistribution member 16 or across all layers of the distribution member16. “Substantially uniformly” may also mean that there is notsignificant pooling of fluid in one area of the distribution memberwhile other areas of the distribution member have less fluid.“Substantially uniformly” may also mean the volume of fluid in one crosssection of the distribution member is similar to the volume of fluid inother similarly sized cross sections of the distribution member.“Substantially uniformly” may also mean that the difference in fluidfrom section to section across the distribution member is small enoughsuch that the application of the dressing 16 to the skin defect willresult in consistent delivery to various areas of the skin defect.

The material of the distribution member 16 may allow for movement or thespread of fluid substantially uniformly across the distribution memberby wicking action. The term “wicking action,” “wicking,” or “wick” asused herein throughout may include or may be used interchangeably withmovement of fluid by capillary action, surface tension, hydrophobicaction, hydrophilic action, or similar types of forces that can move afluid. Orientation independence for example, may mean that the dressing16 m may be fed from the top and oriented vertically. The dressing 16 bis oriented vertically, but fed horizontally, while, the dressing 16 qis oriented horizontally and fed horizontally. The dressing 16 r isoriented vertically, and fed from below. In all of illustratedembodiments in FIG. 6, the orientation of the dressing 16 may beineffectual to inhibit distribution.

In embodiment, the distribution member comprises at least one materialchosen from a polymer, a woven fabric, a non-woven fabric, a naturallyoccurring fiber, a sponge, a fiber matrix, a gauze, absorbent material,adsorbent material, a gel, and a foam. In one embodiment, thedistribution member 16 is a porous pouch.

Within the bounds dictated by physics and engineering, the capillaryaction of the distribution member 40 will draw a liquid upward. Also,“kiss-through” tacking of the outermost members of the dressing togetherwill resist accumulation within the dressing. For example, adistribution member 40 may be bonded to a protective member 39 atregular intervals along a line, across a grid, or the like. Accordingly,two members not allowed to separate more than a nominal distance resistfluid accumulation.

However, by properly sizing the pore size composition, construction,thereby creating specific hydrophobic/hydrophilic interactions, surfacetension affect, or capillary force affect of the distribution member 40,a dressing 16 may constructed of the distribution member 40 toeffectively defy gravity and distribute the medicament, even upward froma location where introduced. Accordingly, the distribution member 40 mayreceive and distribute the fluid substantially uniformly across thedistribution member, irrespective of the orientation of the distributionmember.

In this embodiment, the distribution member 40 maintains a predeterminedamount of fluid substantially uniformly across the distribution member.The distribution member 40 may in some configurations release fluid at asaturation point of level of the distribution member 40. In otherembodiments, the release of fluid by the distribution member 40 mayoccur before or after that time. It will be appreciated by those ofskill in the art that the rate and amount of fluid into the distributionmember 40, coupled with the pore size of the distribution member 40 andthe structure of adjacent members may be used to determine at what pointthe distribution member 40 may release fluid and also to what extent thefluid is distributed throughout the distribution member 40. It willfurther be appreciated by those of skill in the art that by having adistribution member configured to uniformly distribute fluid, or inother words, to have similar amounts of fluid occupy the different areasof the distribution member 40, that better application of the fluid tothe skin defect can be obtained.

The distribution member 40 was tested in one test by applying thedressing vertically to a sheet of glass. An amount of colored fluid wasapplied to the center of the distribution member and the spread of fluidwas recorded over time. Viewing the recording after various points intime revealed that fluid was radially distributed from the point ofintroduction uniformly in all section of the distribution member despitethe down ward pull of gravity. Thus, at different points in time, theouter boundary of the spreading fluid created substantially concentriccircles under the entire distribution member was filled with fluid.Dozens of tests were performed with substantially similar results.

The configuration of the distribution member 40 of the presentembodiment may also allow the distribution member to maintain aconcentration of active ingredient in the fluid substantially uniformlyacross the distribution member and allow said concentration of activeingredient in the fluid to communicate with the skin defect. Thedistribution member 40 may be engineered to allow the concentration ofthe fluid to be uniformly distributed across the distribution member. Inother words, the distribution member 40 may allow fluid distributionsuch that a concentration of the fluid in one area of the distributionmember is substantially similar to the concentration of the fluid inanother area of the distribution member. By engineering the distributionmember 40 and by choice of active ingredient carrier as discussed above,among other things, the distribution member may maintain a concentrationof active ingredient in the fluid substantially uniformly within apredetermined range of concentration across the distribution member andmay allow said concentration in said range to communicate with the skindefect. In one embodiment, the dressing 16 comprises a feed conduit fordelivering a fluid to a distribution member 40. The distribution member40 receives and distributes the fluid substantially uniformly across thedistribution member 40, irrespective of the orientation of thedistribution member 40. The distribution member 40 comprises materialthat allows the spread of fluid substantially uniformly across thedistribution member 40 by wicking action and can be cut to a desiredsize and still maintain a substantially uniform volume of fluid acrossthe distribution member 40.

Referring to FIG. 7, in certain embodiments, a dressing 16 may includeone or many members to accomplish their respective functions. Forexample, in the illustrated embodiment, a member 92 may be a protectivemember 92. Protective members 92 are typically installed to preventpuncture, abrasion, snagging, evaporation, wetting, soiling, and thelike. A protective member 92 may operate to provide multiple functions.It will be appreciated by those of skill in the art that the protectivemember 92 may be the protective member 39 discussed above.

For example, a durable fabric may be used as an protective member 92 topromote evaporation and aeration while still protecting againstpuncture, snagging, abrasion, wear, and the like. Meanwhile, othermembers such as polymeric materials may minimize access to air, optimizeevaporation of fluids, or the like. Accordingly, the protective member92 may be designed according to the functionality desired.

In certain embodiments, the member 93 may be a stay-dry (hydrophobic)lining. For example, because a wicking layer 95 will tend to draw afluid from a transport wicking layer 94, the wicking layer 94 may needto be separated by a stay-dry liner 93. Accordingly, the lining member93 rejects transport of liquids therethrough, therein, or both. Liquidspreferentially stay in the wicking layer 94.

The functions of the members 92 and 93 may be reversed. For example, astay-dry material may form the protective member 92. As a practicalmatter, the structurally protective member 92 typically serves best asthe outermost member. Accordingly, the protective member 92, may itselfneed to be protected against wicking from liquids being transported in awicking transport member 94. Thus, a stay-dry lining member 93 rejectsthe transport of liquid from the wicking layer 94 into either of theprotective member 92 and the outside environment.

A stay-dry lining member 93 resists wicking into the protective member92. For example, if a dressing 16 is laden with liquid fluid, typicallysaturated, then the fluid may be wicked out into such items as cottonbed clothes, bedding, and the like. Accordingly, a stay-dry lining 93may resist the transport of liquid out of the transport wicking layer94. If the protective member 92 is imperious to liquid, then a stay-drylinen member 93 may not be required.

On the other hand, where aeration or evaporation is desired, theprotective member 92 may be primarily a mechanical protection, veryporous and susceptible to absorbing liquid from an optional transportwicking layer 94. The wicking layer 95 is typically formed of a materialhaving a smaller effective pore size than that of the protective member92 or the transport wicking layer 94. Accordingly, the wicking material95 preferentially attracts fluids from the transport wicking layer 94.Thus the wicking layer 95 may be the principle delivery member for theskin defect. The stay-dry member 93 may be integral with or one and thesame as the protective member 92 and the protective member 92 may haveall the characteristics and functionality of the stay-dry member 93.

Having two wicking layers 94, 95 is optional. Either may suffice.However a smaller pore size promotes delivery independent fromorientation, while larger pore size promotes faster capillary transport.A member 94 may thus be thought of as a distribution member. Thedistribution member 94 may provide a pore size (e.g. interstitial gap,etc.) having less resistance to flow then the wicking layer 95. It willbe appreciated by those of skill in the art that the distribution member94 may also be the distribution member 40 and/or 68 b described above.

Meanwhile, a non-adhering interface member 96 may cover the principalwicking layer 95 which may be part of the distribution member. Theinterface member 96 may be the same interface member 78 described above.Dimensions of the dressing 16 of FIG. 7 may be selected as appropriate.For example, the scales or sizes of the thickness of the non-adheringinterface member 96 and the wicking distribution member 95 areeffectively polar opposites. The non-adhering interface member 96 (if asolid polymer) is typically as thin as possible and perforated in orderto promote transport of the fluid from the wicking layer 95. If thenon-adhering interface member 96 is a gel, it may diffuse an activeingredient with or without the carrier to the treated skin defect. A gelmay also largely liquefy or disintegrate (to a greater or lesser extent,depending on formulation) in the presence of liquids, promoting directdelivery of a liquid from a wicking layer 95 to skin defect.

In one embodiment, the interface member 96 is positioned between thedistribution member 94 and a skin defect being treated by the dressing16. The interface member 96 configured to transport the fluid intocontact with the skin defect. The protective member 92 may be positionedadjacent to the distribution member 94. As discussed above, theprotective member 92 may protect the distribution member 94 from loss offunctionality. For example, if the distribution member 94 is damaged insome way or clogged or if the structure is altered, the distributionmember 94 may not spread the fluid substantially uniformly. Furthermore,the protective member 92 may be semi-occlusive and may aid in directingfluid out of the distribution member 94 and onto the skin defect. Thus,the protective member 92 might ensure ability of moisture or vapors toleave the distribution member and to leave the dressing in order tobalance the moisture content of the dressing and thus the fluid levelbalance in the skin defect.

The dressing 16 of FIG. 7 may be configured with any of the members92-96 shown, some of them, or additional members, as desired. Typically,any of the dressings 16 discussed hereinabove may be made with one ormore of the members 92-96 illustrated in the dressing 16. Accordingly, amulti member dressing 16 may be engineered to accomplish its functionsin the most effective way by using the appropriate selection of members92-96. The multi-member dressing may include a wicking layer receivingthe fluid, a barrier member that may or may not be configured to protectthe dressing from the environment and provide for vapor transmission, atransfer member to transfer the fluid to the distribution member, anfluid absorber member to absorb excessive fluid being delivered or forabsorbing the wound exudate, a tenting member positioned at the rim ofthe dressing to provide for lateral evaporation, and an interface memberbetween the wicking layer and the treated skin defect to transfer thefluid thereto from the wicking layer while performing any other functionneeded, such as sealing, anti-adhesion, or the like. Alternatively, thedressing may comprise at least one functional member consisting of adistribution member an interface member, a transport member, aprotective member, and an absorption member. Any of said members couldbe integrated to achieve multiple functions in one or more members.Thus, one or more of the members 92-96 may be structured to operate asat least one of an interface member, a distribution member, a fluidtransport member, a protective member, a tenting member, a fluidabsorber, and a combination thereof.

Referring to FIG. 8, a controller 100 may control an electrochemicalreactor 98 producing byproducts 101 or gasses 101. These byproducts 101a, 101 b are generated in response to the spontaneous flow of electronsand ions in the electrochemical reactor 98 or galvanic cell 98. Theactive members 102, 106 may contribute or consume electrons. Either onemay generate a byproduct 101 that becomes a gas for the reservoir 22(FIGS. 1 and 2).

Often, one material 102, 106 may create a byproduct 101 as a gas, whilethe other material 106, 102 produces a byproduct that stays in solutionor plates out at a surface of the other active material 106, 102. Aseparator 104 may or may not be used in-between the two activematerials. Regardless of the chemistry, or the mechanism, theelectrochemical reactor 98 may be made to generate a byproduct 101 in agaseous state by choosing the chemistry of the electrodes 102, 106 andcontrolling the electrical current through a circuit 107.

In the illustrated embodiment, the electricity generated or the currentgenerated through the circuit 107 is not the object, but rather thebyproduct gasses that are discharged as a result of the flow ofelectrons. However, such a battery or galvanic cell 98 is designed tooptimize the generation of the byproduct 101, rather than optimizing theoutput of electricity through the circuit 107.

The circuit 107 may control electron flow, and thus the generation ofgas. In one basic embodiment, a controller 100 a may include a switch110 to close the circuit 107. To limit the rate of electrochemicalreaction, and thus the generation of gas, some impedance 108, such as aresistor 108, may be in the circuit 107. Thus, a controller 100 in asimplest embodiment may simply be a module 100 a or controller 100 aproviding a physical switch 110 and an impedance 108. In thisembodiment, the switch 110 may selectively open and close.

In some embodiments, the switch may operate a single time to move froman open position to a closed position. In alterative embodiments, theswitch 110 may selectively open again to stop generation of gas. In amore sophisticated embodiment, a controller 100 b may include a controlpanel 112 having a display 114. A user may read instructions or bring upmenus on the display 114. By various buttons 115-118 a user may selectan “on” or “off” condition, provide a rate increase or decrease in theproduction of gas.

In general, a controller 100 b may be a simple analog or digital circuitaccomplishing certain limited functions. Likewise, the controller 100 bmay include additional sophistication.

For example, in one embodiment, a controller 100 c may actually be amicroprocessor-based controller 100 c. For example, in the illustratedembodiment, a central processing unit 120 (CPU 120) may operably connectto a memory device 122. In a typical embodiment, the processor 120 mayoperate controls 124 such as relays, gates, and the like for increasingcurrent flow from a very low rate through the circuit 107 to a very highrate.

In one contemplated embodiment, the processor 120 may receiveinstructions, data, or the like, through an input/output interface 126(I/O interface). For example, sensors 128 may operably connect toprovide inputs to the I/O interface 126. Sensors 128 may monitorpressures, humidity, chemical concentration, electrochemical properties,or the like from the dressing 16 or elsewhere in the system 10and reportthrough the I/O interface 126 to the processor 120 to control the deviceoperation.

The processor 120 may be programmed with an application 130 stored in amemory device 122. Alternatively, the processor 120 may execute theapplication 130 to provide feedback control based on sensors 128 tocontrol a value of a desired property, parameter, or conditionassociated with the dressing 16. For example the pump 12 may becontrolled according to humidity sensed by a sensor 128 within thedressing 16. In such an embodiment, for example, a portion of thedressing 16 may be sensed to determine that the liquid of a fluid hasevaporated or has a certain concentration of a chemical detected.

In general, the pump may be as simple or sophisticated as warranted bycost, medical constraints, or desired controls for applying a fluid to adressing 16. In general, any physical parameter that may be sensed by asensor 128 may be used to control the processor 120 through a suitableapplication 130 programmed to do so. Accordingly, more gas may begenerated by the generator 20, prompting the flow of additional fluidfrom the fluid source 26 through the feed conduit 14 and into thedressing 16.

Typically, the application 130 will operate on top of an operatingsystem 132 or O/S 132. Other functional features may be accomplished byother software 134 executed in the processor 120 based on data 134 inmemory 122. For example, other data 134 may include a history ofoperation of the gas generator 20 by time, chemical, current, gasvolume, or the like. So long as physical equations are known, they canbe programmed into the application 130 to detect and store data 134.Data 134 may also include other applications such as supportingapplications, control applications, data management applications, andthe like.

Referring to FIG. 9, a cross section of a housing 18 may include areservoir 22 storing gas. Likewise, a fluid source 26 may contact areservoir 22. Motion or pressure by the reservoir 22 will result incorresponding motion or pressure in the fluid source 26. Typically, thefluid source 26 may be pre-filled or filled at point of use. In theillustrated embodiment, the reservoir 22 and fluid source 26 may beinstalled such that initially the gas reservoir 22 occupies very littleor comparatively little space. Meanwhile, upon filling, either at afactory or at point of use, the fluid source 26 typically occupies themajority of the space within the housing 18.

As gas is generated in the gas reservoir 22, it displaces space occupiedby the fluid source 26, discharging the fluid through an outlet fitting32 to a feed conduit 14 and on to a dressing 16. In the illustratedembodiment, the reservoir 22 and fluid source 26 may substantiallyoccupy the available space within the housing 18. The reservoir 22 andfluid source 26 may have elastomeric properties. However, elastomericmaterials may also react with certain fluids.

For example, many fluids involve extremely small amounts of an activeingredient in an overwhelming volume of a carrier. Meanwhile, an activeingredient may be very reactive. Thus, a trace amount of a metal orother contaminant may react with a large amount of an available activeingredient. Thus, the fluid source 26 is better served if made of lessreactive materials.

The fluid source 26 should typically not have any deleterious effect onthe fluid. Likewise, no constituent of the fluid's active ingredient,carrier, or other excipient should attack the integrity of the fluidsource 26 during its operational lifetime. Accordingly, materials,sizes, and properties may be selected to provide an optimum chemicalstability, mechanical integrity, pressure support, and so forth neededfor the particular apparatus 10 and method contemplated.

In certain embodiments, the reservoir 22 and fluid source 26 mayactually have elastic properties (e.g. elastic restrictions, springpistons, etc.) and provide some resisting amount of pressure wheninflated. Alternatively, the reservoir 22 and fluid source 26 may have asubstantially fixed wall area, capable of enclosing a fixed maximumvolume. Accordingly, as either the reservoir 22 or the fluid source 26is filled, it may expand toward its maximum volume without substantialresistance until that point is reached.

Referring to FIG. 10, a reservoir 22 and fluid source 26 may be formedof laminated or bonded layers of materials. The housing may be openableor sealed, disposable or re-usable. The reservoir 22 and fluid source 26need not be limited to a single reservoir each within the housing 18.Multiple reservoirs 22 may be used or multiple fluid sources 26.Likewise, reservoir 22 and fluid source 26 may be replaceable,refillable, or both.

For example, in certain inexpensive embodiments, a very simple switch100 may control a gas generator 20 filling a reservoir 22. The time maybe fixed by the chemistry, size, and so forth of the principle elements102, 104, 106 of the electrochemical reactor 98. A second reservoir 22,with a second gas generator 20 may be useful for operating the apparatus10 a second time, after refilling of the fluid source 26. In such a way,a multi-use, disposable unit may still result with very primitivecontrols 100.

A method for treating a skin defect is also disclosed. The methodincludes providing a dressing or fluid delivery system comprising a feedconduit and a distribution member in fluid communication with the feedconduit. The distribution member is configured to receive a fluid andcomprising a material to substantially uniformly distribute the fluidacross the distribution member irrespective of the orientation of thedistribution member. The dressings and delivery systems described intheir various embodiments and combinations in this application may beused for the dressing or fluid delivery system used in the methodtreating a skin defect.

The method includes applying the dressing to a skin defect and supplyinga fluid to the distribution member through the feed conduit. Supplying afluid in one embodiment may include supplying a pre-determined quantityof fluid containing an active ingredient. Supplying a fluid may alsoinclude priming the dressing with a quantity of fluid. In anotherembodiment, priming the dressing with a quantity of fluid is a separatestep. Supplying a fluid may also include providing a bolus of fluid tothe dressing before or after an initial quantity of fluid is supplied.In one embodiment, supplying a quantity of fluid is provided manuallyfrom a fluid source to the dressing. In another embodiment, fluid isautomatically provided from a fluid source to the dressing. In otherembodiments, the dressing or system may include a controller of the typedescribed herein which may be programmed to supply the fluid at apredetermined flow rate or time interval. The supply of fluid by any ofthese methods may be continuous or at intervals with varying flow rates.

The method includes the step of distributing the fluid substantiallyuniformly across the distribution member. The method also includessubstantially uniformly distributing the fluid to the skin defectirrespective of the orientation the distribution member.

Supplying fluid to the distribution member comprises maintaining a fluidwith a concentration of active ingredient greater than, equal to, orless than a predetermined threshold over a predetermined period of time.This may include maintaining the concentration of the fluid at aminimally therapeutically effective threshold throughout thedistribution member. Supplying a quantity of fluid to the distributionmember may be such that the skin defect receives a concentration of theactive ingredient greater than a therapeutically effective thresholdcorresponding to a minimum inhibitory concentration.

It will be appreciated by those of skill in the art that it may bedesirous to maintain the concentration of the active ingredient below avalue corresponding to a maximum concentration above which the activeingredient causes side effects. Furthermore, a concentration of activeingredient may be selected to substantially minimize the development ofresistance, by a target organism, to the active ingredient, throughout apre-selected period of time. Maintaining a concentration of activeingredient in the distribution member above, at, or below a threshold,such that the desired concentration is applied to the skin defect may bebeneficial to facilitate pain or inflammation reduction or to promotehealing of the tissue.

The method may also include trimming or cutting the dressing or one ormore layers or member that make up the dressing to a desired shapecorresponding to a treatment area.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrative,and not restrictive. The scope of the invention is, therefore, indicatedby the appended claims, rather than by the foregoing description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

1. A dressing comprising: a feed conduit for delivering a fluid to adistribution member, the distribution member receiving and distributingthe fluid substantially uniformly across the distribution member,irrespective of the orientation of the distribution member.
 2. Thedressing of claim 1, wherein the fluid comprises an active ingredient.3. The dressing of claim 1, wherein an interface member is positionedbetween the distribution member and a skin defect being treated by thedressing, the interface member transporting the fluid from thedistribution member into contact with a skin defect.
 4. The dressing ofclaim 3, wherein the interface member comprises at least one materialchosen from a non-adhering polymer and a bioabsorbable polymer.
 5. Thedressing of claim 3, wherein the interface member comprises at least onestructure chosen from a sheet, a foam, a gel, gauze, a porous matrix, ahoneycomb, a mop of fibrous material, a comminuted fibrous material, anda tubular structure.
 6. The dressing of claim 1, wherein thedistribution member maintains a predetermined amount of fluidsubstantially uniformly across the distribution member and allows saiddistribution of fluid to communicate with a skin defect.
 7. The dressingof claim 1, wherein the distribution member maintains a concentration ofactive ingredient in the fluid substantially uniformly across thedistribution member and allows said concentration of active ingredientin the fluid to communicate with a skin defect.
 8. The dressing of claim1, wherein the distribution member maintains a concentration of activeingredient in the fluid substantially uniformly within a predeterminedrange of concentration across the distribution member and allows saidconcentration in said range to communicate with a skin defect.
 9. Thedressing of claim 1, wherein the distribution member comprises materialthat allows the spread of fluid substantially uniformly across thedistribution member by wicking action.
 10. The dressing of claim 9,wherein the force exerted on the fluid by the wicking action is greaterthan or equal to the force exerted on the fluid by gravity.
 11. Thedressing of claim 9, wherein the distribution member comprises at leastone material chosen from a polymer, a woven fabric, a non-woven fabric,a naturally occurring fiber, a sponge, a fiber matrix, a gauze,absorbent material, adsorbent material, a gel, and a foam.
 12. Thedressing of claim 1, further comprising a protective member positionedadjacent the distribution member.
 13. The dressing of claim 12, whereinthe protective member is semi-occlusive.
 14. The dressing of claim 1,wherein the feed conduit is connected to a fluid source for replenishingthe fluid in the distribution member with or without additional humanintervention.
 15. The dressing of claim 14, wherein the fluid sourcecontrols a fluid flow to the distribution member.
 16. The dressing ofclaim 1, comprising one or more members structured to operate as atleast one of an interface member, a distribution member, a fluidtransport member, a protective member, a tenting member, a fluidabsorber, and a combination thereof.
 17. The dressing of claim 1,wherein the distribution member or dressing is configured to be cut to adesired size and still maintain a substantially uniform volume of fluidacross the distribution member.
 18. The dressing of claim 1, wherein thedistribution member comprises distribution tubes for distributing avolume of fluid substantially uniformly across the distribution member.19. The dressing of claim 1, wherein the distribution member comprises aporous pouch.
 20. A dressing comprising: a feed conduit for delivering afluid to a distribution member, the distribution member receiving anddistributing the fluid substantially uniformly across the distributionmember, irrespective of the orientation of the distribution member;wherein the distribution member comprises material that allows thespread of fluid substantially uniformly across the distribution memberby wicking action; and wherein the distribution member is configured tobe cut to a desired size and still maintain a substantially uniformvolume of fluid across the distribution member.
 21. A dressingcomprising: a distribution member; a feed conduit for delivering a fluidto the distribution member, the distribution member configured toreceive and distribute the fluid substantially uniformly across thedistribution member by wicking action, irrespective of the orientationof the distribution member; and an interface member is positionedbetween the distribution member and a skin defect being treated by thedressing, the interface member transporting the fluid into contact withthe skin defect.
 22. The dressing of claim 21, wherein the distributionmember maintains a predetermined amount of fluid substantially uniformlyacross the distribution member.
 23. The dressing of claim 22, whereinthe distribution member maintains a concentration of active ingredientin the fluid substantially uniformly across the distribution member andallows said concentration of active ingredient in the fluid tocommunicate with the skin defect.
 24. The dressing of claim 23, whereinthe distribution member maintains a concentration of active ingredientin the fluid substantially uniformly within a predetermined range ofconcentration across the distribution member and allows saidconcentration in said range to communicate with the skin defect.
 25. Thedressing of claim 21, further comprising a protective member positionedadjacent the distribution member.
 26. The dressing of claim 25, whereinthe protective member is semi-occlusive.
 27. The dressing of claim 25,comprising one or more members structured to operate as at least one ofthe interface member, the distribution member, and the protectivemember, a fluid transport member, a tenting member, a fluid absorber,and a combination thereof.
 28. The dressing of claim 21, wherein thedistribution member is configured to be cut to a desired size and stillmaintain a substantially uniform volume of fluid across the distributionmember.
 29. A dressing comprising: a distribution member comprising atleast one material chosen from a polymer, a woven fabric, a non-wovenfabric, a naturally occurring fiber, a sponge, a fiber matrix, a gauze,absorbent material, adsorbent material, a gel, and a foam; a feedconduit for delivering a fluid to the distribution member, thedistribution member configured to receive and distribute the fluidsubstantially uniformly across the distribution member by wickingaction, wherein the force exerted on the fluid by the wicking action isgreater than the force exerted on the fluid by gravity, and wherein thedistribution member is configured to maintain a predetermined amount offluid substantially uniformly across the distribution member, whereinthe fluid is received, distributed, and maintained irrespective of theorientation of the distribution member; an interface member ispositioned between the distribution member and a skin defect beingtreated by the dressing, the interface member transporting the fluidinto contact with the skin defect, wherein the interface membercomprises at least one material chosen from a non-adhering polymer and abioabsorbable polymer; and a semi-occlusive protective member positionedadjacent the distribution member.
 30. The dressing of claim 29, whereinthe distribution member maintains a concentration of active ingredientin the fluid substantially uniformly across the distribution member andallows said concentration of active ingredient in the fluid tocommunicate with the skin defect.
 31. The dressing of claim 30, whereinthe distribution member maintains a concentration of active ingredientin the fluid substantially uniformly within a predetermined range ofconcentration across the distribution member and allows saidconcentration in said range to communicate with the skin defect.
 32. Thedressing of claim 31, wherein the distribution member is configured tobe cut to a desired size and still maintain a substantially uniformvolume of fluid across the distribution member
 33. The dressing of claim32, comprising one or more members structured to operate as at least oneof the interface member, the distribution member, the protective member,a fluid transport member, a tenting member, a fluid absorber, and acombination thereof.
 34. A method for treating a skin defect, the methodcomprising: providing a dressing comprising: a feed conduit; and adistribution member in fluid communication with the feed conduit, thedistribution member configured to receive a fluid and comprising amaterial to substantially uniformly distribute the fluid across thedistribution member irrespective of the orientation of the distributionmember; applying the dressing to a skin defect; supplying a fluid to thedistribution member through the feed conduit; and distributing the fluidsubstantially uniformly across the distribution member.
 35. The methodof claim 34, wherein the fluid comprises an active ingredient.
 36. Themethod of claim 34, wherein an interface member is positioned betweenthe distribution member and the skin defect being treated by thedressing, the interface member transporting the fluid into contact withthe skin defect.
 37. The method of claim 34, wherein the distributionmember maintains a predetermined amount of fluid substantially uniformlyacross the distribution member.
 38. The method of claim 35, wherein thedistribution member maintains a concentration of active ingredient inthe fluid substantially uniformly across the distribution member andallows said concentration of active ingredient in the fluid tocommunicate with the skin defect.
 39. The method of claim 35, whereinthe distribution member maintains a concentration of active ingredientin the fluid substantially uniformly within a predetermined range ofconcentration across the distribution member and allows saidconcentration in said range to communicate with the skin defect.
 40. Themethod of claim 34, wherein the distribution member comprises materialthat allows the spread of fluid substantially uniformly across thedistribution member by wicking action.
 41. The method of claim 40, wherethe force exerted on the fluid by the wicking action is greater than orequal to the force exerted on the fluid by gravity.
 42. The method ofclaim 34, further comprising a protective member positioned adjacent thedistribution member.
 43. The method of claim 34, wherein thedistribution member comprises distribution tubes for distributing avolume of fluid substantially uniformly across the distribution member.44. The method of claim 34, wherein the distribution member comprises aporous pouch.
 45. The method of claim 34, wherein supplying a fluidcomprises supplying a pre-determined quantity of fluid containing anactive ingredient.
 46. The method of claim 34, further comprisingpriming the dressing with a quantity of fluid.
 47. The method of claim34, further comprising providing a bolus of fluid to the dressing. 48.The method of claim 34, further comprising manually providing fluid froma fluid source to the dressing.
 49. The method of claim 34, furthercomprising automatically providing fluid from a fluid source to thedressing.
 50. The method of claim 34, wherein the dressing furthercomprises a controller, and wherein supplying the fluid to thedistribution member comprises programming the controller to supply thefluid at a predetermined flow rate or time interval.
 51. The method ofclaim 34, further comprises substantially uniformly distributing thefluid to the skin defect from the distribution member.
 52. The method ofclaim 35, wherein supplying fluid to the distribution member comprisesmaintaining a fluid with a concentration of active ingredient greaterthan a predetermined threshold over a predetermined period of time. 53.The method of claim 35, wherein supplying fluid to the distributionmember comprises maintaining a fluid with a concentration of activeingredient lesser than a predetermined threshold over a predeterminedperiod of time.
 54. The method of claim 35, wherein the activeingredient comprises at least one composition chosen from anantimicrobial, an antibiotic, an antifungal, an antiviral, anantiseptic, and an antibacterial agent.
 55. The method of claim 35,wherein the active ingredient comprises at least one composition chosenfrom an analgesic, a palliative, and an anti-inflammatory agent.
 56. Themethod of claim 35, wherein the active ingredient comprises at least onecomposition chosen from de-ionized water, a polymeric gel, a salinecomposition, and a hydrocolloid.
 57. The method of claim 35, wherein theactive ingredient comprises at least one beneficial agent chosen from anenzymatic debrider, a tissue growth factor, a scar-reducing agent,tissue cells, topical nutrients, a coagulant, nitric oxide, oxygen gas,ozone, and a gene therapy agent.
 58. The method of claim 35, wherein theactive ingredient is selected to be therapeutically effective intreating a dermatological disorder chosen from a skin defect, an allergyeruption, a skin cancer, a rash, a burn, a growth, a cyst, a wart, atumor, an ulcer, a boil, an incision, a graft, oiliness, dryness,wrinkles, blemishes, discolorations, and trauma.
 59. The method of claim34, further comprising trimming the dressing to a desired shapecorresponding to a treatment area.
 60. A method for treating a skindefect, the method comprising: providing a dressing comprising: a feedconduit; and a distribution member in fluid communication with the feedconduit, the distribution member configured to receive a fluid andcomprising a material to substantially uniformly distribute the fluidacross the distribution member irrespective of the orientation of thedistribution member; cutting the dressing to a desired shape; applyingthe dressing to a skin defect; supplying a fluid having an activeingredient to the distribution member through the feed conduit;distributing the fluid substantially uniformly across the distributionmember; and distributing the fluid substantially uniformly to a skindefect irrespective of the orientation the distribution member.
 61. Themethod of claim 60, further comprising priming the dressing with aquantity of fluid.
 62. The method of claim 60, further comprisingproviding a bolus of fluid to the dressing.
 63. The method of claim 60,further comprising automatically controlling the supply of fluid to thedistribution member.
 64. The method of claim 63, wherein controlling thesupply of fluid comprises programming a controller to supply the fluidat a predetermined flow rate or time interval.
 65. The method of claim64, wherein supplying fluid to the distribution member comprisesmaintaining a fluid with a concentration of active ingredient greaterthan a predetermined threshold over a predetermined period of time. 66.The method of claim 65, wherein supplying fluid to the distributionmember comprises maintaining a fluid with a concentration of activeingredient lesser than a predetermined threshold over a predeterminedperiod of time.
 67. The method of claim 60, comprising one or moremembers structured to operate as at least one of an interface member, adistribution member, and a protective member.
 68. A fluid deliverysystem comprising: a housing having, an interior volume, inextensibleand vented to discharge gas therefrom, and containing reservoir and afluid source in contact with one another; a fluid source containing afluid having a first wall flexible to move in response to substantiallyany pressure and substantially impervious to the fluid, and an outlet todispense the fluid; a reservoir comprising a second wall, in contactwith the first wall to move therewith, substantially impervious to agas; a galvanic cell in communication with the reservoir and comprisingchemicals selected to produce a gas within the reservoir; a dressing toexpose the fluid to a skin defect of a subject, said dressing comprisinga distribution member configured to receive the fluid and comprising amaterial to substantially uniformly distribute the fluid across thedistribution member by wicking action irrespective of the orientation ofthe distribution member; and a conduit connectable to the outlet and influid communication with the distribution member to replenish the fluidin the distribution member.
 69. The fluid delivery system of claim 68,wherein the fluid comprises an active ingredient.
 70. The fluid deliverysystem of claim 68, wherein the dressing further comprises a protectivemember positioned adjacent the distribution member.
 71. The fluiddelivery system of claim 70, wherein the protective member issemi-occlusive.
 72. The fluid delivery system of claim 68, wherein aninterface member is positioned between the distribution member and askin defect being treated by the dressing, the interface membertransporting the fluid into contact with the skin defect.
 73. The fluiddelivery system of claim 68, wherein the distribution member comprisesmaterial that allows the spread of fluid substantially uniformly acrossthe distribution member by wicking action.
 74. The fluid delivery systemof claim 73, wherein the force exerted on the fluid by the wickingaction is greater than or equal to the force exerted on the fluid bygravity.
 75. The fluid delivery system of claim 68, wherein thedistribution member comprises distribution tubes for distributing avolume of fluid substantially uniformly across the distribution member.76. The fluid delivery system of claim 68, wherein the distributionmember comprises a porous pouch.
 77. The fluid delivery system of claim68, wherein the distribution member maintains a substantially uniformfluid volume across the distribution member and allows the fluid tocommunicate with the skin defect upon reaching or exceeding apredetermined saturation level.
 78. The dressing of claim 68, whereinthe distribution member maintains a concentration of active ingredientin the fluid substantially uniformly across the distribution member andallows said concentration of active ingredient in the fluid tocommunicate with the skin defect.
 79. The dressing of claim 68, whereinthe distribution member maintains a concentration of active ingredientin the fluid substantially uniformly within a predetermined range ofconcentration across the distribution member and allows saidconcentration in said range to communicate with the skin defect.
 80. Thefluid delivery system of claim 68, wherein the fluid source outletcomprises a regulator to maintain pressure in the fluid source greaterthan the ambient pressure to minimize operational variations due tovariations in at least one of the ambient temperature, the barometricpressure, or the orientation of the device.
 81. The fluid deliverysystem of claim 68, further comprising a controller connected to thegalvanic cell in a circuit to control the generation of the gas in thereservoir, thereby controlling a delivery rate of the fluid from thefluid source.
 82. The fluid delivery system of claim 81, wherein thecontroller comprises a fixed or variable resistor and a switch.
 83. Thefluid delivery system of claim 81, wherein at least a portion of thecontroller is located separately from the galvanic cell and is incommunication with the cell by at least one of mechanical hardware,electromagnetic, radio frequency, magnetic, or optical feedback orcircuit.
 84. The fluid delivery system of claim 81, wherein thecontroller is located inside the reservoir.
 85. The fluid deliverysystem of claim 81, wherein the controller further comprises a processorprogrammatically controlling the value of resistance in the circuit. 86.The fluid delivery system of claim 85, further comprising a fill port influid communication with the fluid source.
 87. The fluid delivery systemof claim 86, wherein the fill port comprises a septum through which asyringe may penetrate to access the fluid source.
 88. The fluid deliverysystem of claim 68, further comprising a sensor operably connected toprovide inputs to the processor to control the value of resistance inaccordance with an algorithm therewith.